Hi Mark,
If you can hear the outgoing packet on a second radio then presumably the PTT is working. The most likely problem is the volume, which you have set to 75, based on the images you included.
I would try playing around with that - likely to a lower setting. This will depend on the radio you're using, any mic gain settings on that radio, etc.
The other suggestion I would have made would be to increase the Tx delay under TNC settings, but it looks as if you have already increased that to 500ms. This can help address problems in a slow response from the PTT command.
It shouldn't really matter but it looks as if you have enabled the option for PTT using "PTT tone". Everything should still work if you switch that off, as presumably the AIOC is using DTR for PTT control, and the digirig is using RTS.
Hope that help,s
Andrew
VA7YAA